Difference between revisions of "Logic family"
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| − | In generic terms, a '''logic family''' is a group of [[logic]] devices which use common supply [[voltage]](s), and common [[analog]] interfacing rules. | + | In generic terms, a '''logic family''' is a group of [[logic]] devices which use common supply [[voltage]](s), and common [[analog]] interfacing rules for their use in [[circuit]]ry. |
For example, in the [[transistor-transistor logic|TTL]] family, 'true' is normally a high (+5V) output, and 'false' is [[ground]]. (The meanings may be reversed when [[negative logic]] is in use, but the voltage levels remain.) | For example, in the [[transistor-transistor logic|TTL]] family, 'true' is normally a high (+5V) output, and 'false' is [[ground]]. (The meanings may be reversed when [[negative logic]] is in use, but the voltage levels remain.) | ||
Revision as of 13:03, 14 October 2018
In generic terms, a logic family is a group of logic devices which use common supply voltage(s), and common analog interfacing rules for their use in circuitry.
For example, in the TTL family, 'true' is normally a high (+5V) output, and 'false' is ground. (The meanings may be reversed when negative logic is in use, but the voltage levels remain.)
For a low output, a TTL chip will generally sink current into itself through the output pin (so that the signal direction is different at the logical and analog levels), send it to ground; for high output, it will source a small amount of current (at the 'high' voltage).
In commercial/marketing terms, a logic family is a line of compatible devices produced by particular manufacturer; e.g. TTL started life as a line of chips from Texas Instruments, before it became effectively a standard.
